What are two common methods when using a public key infrastructure for maintaining access to servers in a network?

A.
ACL and PGP.

B.
PIM and CRL.

C.
CRL and OCSP.

D.
RSA and MD2

Explanation:
The process of revoking a certificate begins when the CA is notified that a particular certificate needs to be revoked. The CA marks the certificate as revoked. This information is published in the CRL and becomes available using OCSP.
Reference: Security + (SYBEX) page 338